Functional seizures: Cluster analysis may predict the associated risk factors.

OBJECTIVES

We applied the Two-Step cluster analysis on a large cohort of patients with functional seizures (FS). We studied whether the background risk factors differed between the patient clusters.

METHODS

All patients with a diagnosis of FS were studied at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2021. The Two-Step cluster analysis was applied considering the age at onset, sex, and seizure semiology. We also studied whether the background risk factors (e.g., a history of sexual abuse, physical abuse, etc.) differed between these patient clusters.

RESULTS

Three-hundred and fifty four patients were studied. The Two-Step cluster analysis was applied to the 230 patients who reported any associated risk factors; there were three clusters of patients. The most prominent feature of cluster 1 included akinetic seizures. The most prominent features of cluster 2 included motor seizures and no ictal injury. The most prominent features of cluster 3 included motor seizures with ictal injury. Compared with patients in cluster 3, a history of sexual abuse was more often reported by patients in cluster 1 (OR: 3.26, 95%CI: 1.12-9.47; p = 0.03). Compared with patients in cluster 3, a history of physical abuse was less often reported by patients in cluster 2 (OR: 0.45, 95%CI: 0.22-0.90; p = 0.026).

CONCLUSION

The Two-Step cluster analysis could identify three distinct clusters of patients based on their demographic and clinical characteristics. These clusters had correlations with the associated risk factors in patients with FS.